Fluid Diode

ABSTRACT

A fluid diode makes use of passive airflow structures to introduce differential flow resistance to airflows moving in forward and reverse directions. The use of a fluid diode in a vaping device and pod allows for an increased flow resistance to airflows moving through the pod in the reverse direction. These airflow in a reverse direction are often associated with a user blowing into the pod, and pushing moisture laden air out of the pod and into the device. By increasing the flow resistance to these reverse airflow, user exhalation into the pod will be resisted and redirected at source.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the first application for the instant invention.

TECHNICAL FIELD

This application relates generally to a mechanism to address backflow and user exhaust, and more particularly to a pod for use in conjunction with an electronic cigarette or vaporizer having a flow diode to prevent backflow.

BACKGROUND

Electronic cigarettes and vaporizers are well regarded tools in smoking cessation. In some instances, these devices are also referred to as an electronic nicotine delivery system (ENDS). A nicotine based liquid solution, commonly referred to as e-liquid, often paired with a flavoring, is atomized in the ENDS for inhalation by a user. In some embodiments, e-liquid is stored in a cartridge or pod, which is a removable assembly having a reservoir from which the e-liquid is drawn towards a heating element by capillary action through a wick. In many such ENDS, the pod is removable, disposable, and is sold pre-filled.

In some ENDS, a refillable tank is provided, and a user can purchase a vaporizable solution with which to fill the tank. This refillable tank is often not removable, and is not intended for replacement. A fillable tank allows the user to control the fill level as desired. Disposable pods are typically designed to carry a fixed amount of vaporizable liquid, and are intended for disposal after consumption of the e-liquid. The ENDS cartridges, unlike the aforementioned tanks, are not typically designed to be refilled. Each cartridge stores a predefined quantity of e-liquid, often in the range of 0.5 to 3 ml. In ENDS systems, the e-liquid is typically composed of a combination of any of vegetable glycerine, propylene glycol, nicotine and flavorings. In systems designed for the delivery of other compounds, different compositions may be used.

In the manufacturing of the disposable cartridge, different techniques are used for different cartridge designs. Typically, the cartridge has a wick that allows e-liquid to be drawn from the e-liquid reservoir to an atomization chamber. In the atomization chamber, a heating element in communication with the wick is heated to encourage aerosolization of the e-liquid. The aerosolized e-liquid can be drawn through a defined air flow passage towards a user's mouth.

FIGS. 1A, 1B and 1C provide front, side and bottom views of an exemplary pod 50. Pod 50 is composed of a reservoir 52 having an air flow passage 54, and an end cap assembly 56 that is used to seal an open end of the reservoir 52. End cap assembly has wick feed lines 58 which allow e-liquid stored in reservoir 52 to be provided to a wick (not shown in FIG. 1). To ensure that e-liquid stored in reservoir 52 stays in the reservoir and does not seep or leak out, and to ensure that end cap assembly 56 remains in place after assembly, seals 60 can be used to ensure a more secure seating of the end cap assembly 56 in the reservoir 52. In the illustrated embodiment, seals 60 may be implemented through the use of o-rings.

As noted above, pod 50 includes a wick that is heated to atomize the e-liquid. To provide power to the wick heater, electrical contacts 62 are placed at the bottom of the pod 50. In the illustrated embodiment, the electrical contacts 62 are illustrated as circular. The particular shape of the electrical contacts 62 should be understood to not necessarily germane to the function of the pod 50.

Because an ENDS device is intended to allow a user to draw or inhale as part of the nicotine delivery path, an air inlet 64 is provided on the bottom of pod 50. Air inlet 64 allows air to flow into a pre-wick air path through end cap assembly 56. The air flow path extends through an atomization chamber and then through post wick air flow passage 54.

A mouthpiece 68 can be attached to the pod 50, typically using a friction fit, or through the use of engaging tabs. The mouthpiece 68 can create a mixing chamber by capping off the post wick airflow passage 54, especially in embodiments where the passage 54 widens as it approaches the end of pod 50. In some embodiments, an absorptive pad 66, also referred to as a spit back pad, can be inserted between the reservoir 52 and mouthpiece 68. Due to the manner in which droplets behave in the post wick airflow passage 54, large droplets that contribute to a phenomenon referred to as spitback, are likely to be pushed to the outer edge of the mixing chamber. The spitback pad 66 can absorb these droplets to prevent them from remaining in the mixing chamber.

FIG. 2 illustrates a cross section taken along line A in FIG. 1B. This cross section of the pod 100 (without the mouthpiece and spitback pad) is shown with a complete (non-sectioned) wick 66 and heater 68. End cap assembly 56 resiliently mounts to an end of air flow passage 54 in a manner that allows air inlet 64 to form a complete air path through pod 50. This connection allows airflow from air inlet 64 to connect to the post air flow path through passage 54 through atomization chamber 70. Within atomization chamber 70 is both wick 66 and heater 68. When power is applied to contacts 62, the temperature of the heater increases and allows for the volatilization of e-liquid that is drawn across wick 66.

Typically the heater 68 reaches temperatures well in excess of the vaporization temperature of the e-liquid. This allows for the rapid creation of a vapor bubble next to the heater 68. As power continues to be applied the vapor bubble increases in size, and reduces the thickness of the bubble wall. At the point at which the vapor pressure exceeds the surface tension the bubble will burst and release a mix of the vapor and the e-liquid that formed the wall of the bubble. The e-liquid is released in the form of aerosolized particles and droplets of varying sizes. These particles are drawn into the air flow and into post wick air flow passage 54 and towards the user.

User experience of an ENDS is related to a number of factors including the delivery of nicotine and the flavor compounds in the e-liquid. The size of the droplets entrained by the airflow, after the bubble pops, is associated with a number of different experiences. Flavor compounds are best experienced by smaller particle sizes. Larger particles are less likely to impart flavour, and are associated with other negative experiences including an effect referred to above as spitback.

With some ENDS that make use of a user activated switch to power the heater in place of a pressure sensor, users are recommended to not power on the heater until after the user starts drawing on the device, or to reduce the power provided to the heater.

FIG. 3 illustrates a pod 76 having a different construction than pod 50. Those skilled in the art will appreciate that the functioning of the pod 76 is quite similar despite the different construction. Pod 76 has a reservoir 78, with a post-wick air flow passage 80, and an end cap assembly 82. End cap 82 includes electrical contacts 84, a pre-wick air flow passage 86, and an atomization chamber 88. Within atomization chamber 88 is wick 90. Heater 92 is connected to electrical contacts 84, and when provided power by a vaping device, heater 92 will be raised to a temperature that causes vaporization of the e-liquid adjacent to heater 92. This vaporization will create a bubble that will expand under the vapor pressure until the surface tension of the e-liquid is no longer strong enough to hold the bubble together. At this point the bubble will rupture and vapor and droplets of varying sizes will be entrained within an airflow moving from pre-wick airflow passage 86, through atomization chamber 88 and into post-wick airflow passage 80. The e-liquid adjacent to the heater 92 is drawn across wick 90, typically through a capillary flow, and is fed from reservoir 78 into the wick through wick feed lines 94.

Backflow is a phenomenon associated with the termination of the airflow through a pod. Typically, when a user draws on a pod, an airflow is created that goes through an airflow passage defined in a pod. In the examples above, the airflow would pass through the pre-wick air flow passage, the atomization chamber and the post wick air flow passage. It has been observed that when a user stops drawing on the device, a backflow occurs, where the airflow reverses. This may not occur through the entirety of the airflow path, and instead may be a localized phenomenon. Backflow can cause two associated, but different problems: it can encourage leaking of e-liquid from the pod, and it allows e-liquid laden air to be pushed backwards through the pod.

Some users keep a vaping device in their mouth, typically held loosely between their lips, when not using the device. As a user exhales, especially immediately after using the device, e-liquid laden air is pushed into the pod. When referring to e-liquid laden air it should be understood that this term refers to air, typically within an airflow, that carries at least one of e-liquid vapor and e-liquid droplets of various sizes. Although this is different from the spontaneous backflow discussed above, there are many similarities in the result, in that both e-liquid and e-liquid laden air are pushed through the pod in a direction that was not intended.

Backflow and user exhalation into the device both cause problems, and some effort has been expended into preventing leakage of e-liquid from the bottom of the pod. E-liquid is known to impair the electrical contacts on both the pod and the device. E-liquid that has leaked into a device is typically considered to be a negative user experience, as the user typically has to clean out the device to prevent e-liquid infiltration into the device.

Another, less commonly understood phenomenon is associated with user exhalation into the device. A pod is typically designed around an airflow path intended for air to flow in a single direction (up/towards the user). When the user exhales or breathes into the device, moisture laden air is pushed through the pod in the opposite direction as the intended airflow. This moisture laden air is exhausted from the pod and into the device.

Moisture laden air and e-liquid expelled from the bottom of the pod can have different effects. Within the device are airflow channels used for control purposes, such as a channel that connects to a pressure sensor. Ingress of expelled e-liquid can cause problems with the correct activation of the pressure sensor. There have been a number of attempts to address the issue of e-liquid egress from a pod and ingress into the device. Typically this has involved either elaborate valving systems in pod requiring moving parts, such as ball valves and/or flaps introduced into the post-wick air flow path. In designs implemented in devices, valves are introduced into airflow paths or other intended points of ingress into the device. These designs are typically directed towards preventing the egress of e-liquid from the pod. Because users exhaling into the a pod after use is a behavior that the device manufacturer recommends against, very little attention has been paid to preventing the negative effects it may cause.

Even if a device is provided with a mechanism to prevent ingress of e-liquid, it is often insufficient to prevent the ingress of moisture laden air exhaled into the device through the pod. Full ingress prevention would likely require implementation of seals and other “water proofing” techniques to prevent ingress of exhaled air into the device. Due to a high moisture content, where the moisture is associated with the e-liquid, condensation of the moisture laden air is associated with a number of problems in vaping devices. Condensation of the moisture laden air can contribute to deposition of an e-liquid residue within the device, which can contribute to electrical issues with the circuitry in the device.

It would therefore be beneficial to have a mechanism to further mitigate backflow of both gasses and liquids from vaporizer pods.

SUMMARY

It is an object of the aspects of the present invention to obviate or mitigate the problems of the above-discussed prior art.

Through the use of passive airflow structures, a fluid diode can be created within the airflow path through the pod. In some cases, the fluid diode can be within either the pod or the device, and in some cases can be formed through the interaction of the features of both the pod and the device. The airflow path through the pod has a forward direction and a reverse direction, and extends through the fluid diode. This allows for a set of passive airflow structures to be used to create differential flow resistances for forward and reverse airflows. A low forward resistance allows for a user preference for low flow resistance to be honored, while a high flow resistance for reverse flows encourages redirection of reverse flows at the source. In cases where the reverse flow originates with a user exhaling into a pod, the increased flow resistance can encourage that the exhalation be directed out of the user's mouth and around the pod and vaping device instead of into it.

In accordance with a first aspect of the present invention, there is provided a pod for storing an atomizable liquid. The pod comprises a reserved, an atomization chamber and a fluid diode. The reservoir stores the atomizable liquid, which in some embodiments is an e-liquid comprising at least one of propylene glycol, vegetable glycerin, nicotine and a flavoring. The atomization chamber is within an airflow path that extends through the pod. The atomization chamber houses a heater, and optionally a wick, that atomizes the atomizable liquid into an airflow following an airflow path through the pod. The fluid diode is also a part of the airflow path. It provides a first flow resistance to airflows moving in a forward direction, and a second flow resistance to airflows moving in a reverse direction. The second flow resistance is greater than the first flow resistance. This makes it more difficult to push air through the pod in a reverse direction than it is to draw air through the pod in a forward direction.

In some embodiments, the fluid diode is located within a pre-wick airflow passage, which is optionally connected to the atomization chamber. In some embodiments, the fluid diode makes use of a plurality of passive airflow structures to provide the differential flow resistance. These passive airflow structures may include at least one of an airflow guide and a fence. In some embodiments, the plurality of passive airflow structures comprises a first airflow guide and a first fence. The first airflow guide splits airflows moving in a reverse direction into a plurality of airflows, and directs each of the plurality of airflows towards each other. The first fence provides a narrowed airflow passage towards an end cap inlet. Taken together, the first airflow guide and the first fence increase the flow resistance to airflow moving in the reverse direction. In a further embodiment, a second airflow guide and second fence (which in some embodiments is integrally formed with the first fence) are also present within the fluid diode and arranged as a reflection of the first airflow guide and the first fence.

In some embodiments, the fluid diode connects an end cap inlet to the atomization chamber, and optionally this is an interface between fluid diode and the atomization chamber that is a set of inlets. In some embodiments, the airflow path is arranged about a principal axis. In some embodiments, the fluid diode is oriented to be substantially perpendicular to the principal axis of the airflow path.

In a second aspect of the present invention, there is provided a vaping device. The vaping device controls the application of power to a pod containing an atomizable liquid, which in turn may control the atomization of the liquid in response to a user input. The pod comprises a battery, a set of electrical leads, a processor and a fluid diode. The battery stores power and is typically rechargeable. There is a pathway between the battery and the electrical leads to allow power from the battery to be transmitted from the battery through the leads to the pod. The processor controls the application of power from the battery to the electrical leads in accordance with received user input. The fluid diode is located at a physical interface between a pod and the device, to allow for it to mate with the pod and create an extended airflow path. This extended airflow path is a combination of the airflow path within the pod, and an airflow path within the flow diode. The airflow path within the flow diode allows for differential flow resistances to be provided to airflows moving through the extended airflow path. Thus, a first flow resistance can be provided to flows in the forward direction, while a second flow resistance, greater than the first, can be applied to flows in the reverse direction.

In an embodiment of the second aspect of the present invention, the fluid diode is comprised of a plurality of passive airflow structures. In some embodiments, the plurality of passive airflow structures include at least one of an air flow guide and a fence. In further embodiments, the airflow path within the pod is arranged about a principal axis, and an airflow path through the fluid diode is substantially perpendicular to the principal axis.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described in further detail by way of example only with reference to the accompanying figure in which:

FIG. 1A is a front view of a prior art pod for use in an ENDS, with a cross sectioned mouthpiece;

FIG. 1B is a side view of the pod of FIG. 1A;

FIG. 1C is a bottom view of the pod of FIG. 1A;

FIG. 2 is a cross section view of the pod of FIGS. 1A, 1B and 1C, shown along section line A-A in FIG. 1B;

FIG. 3 is a sectioned view of an alternate embodiment of a pod;

FIG. 4A illustrates a Tesla Valve with a flow in a forward direction;

FIG. 4B illustrates a Tesla Valve with a flow in a reverse direction;

FIG. 5 illustrates a cross section of an end cap having an end cap top and an end cap base;

FIG. 6A is a top view of an end cap base having a fluid diode;

FIG. 6B is a top view of the end cap base of FIG. 6A illustrating forward and reverse air flow paths;

FIG. 7 is a perspective view of the end cap base of FIG. 6A;

FIG. 8 is a top view of an alternate embodiment of an end cap base having a fluid diode; and

FIG. 9 is a perspective view of the end cap base of FIG. 8.

In the above described figures like elements have been described with like numbers where possible.

DETAILED DESCRIPTION

In the instant description, and in the accompanying figures, reference to dimensions may be made. These dimensions are provided for the enablement of a single embodiment and should not be considered to be limiting or essential. Disclosure of numerical range should be understood to not be a reference to an absolute value unless otherwise indicated. Use of the terms about or substantively with regard to a number should be understood to be indicative of an acceptable variation of up to ±10% unless otherwise noted.

Many of the prior art efforts at providing a seal within the pod have been directed to preventing egress of e-liquid. Many of these can be quite effective, such as the use of a capillary seal for the air inlets positioned within a pre-wick airflow path. However, egress of e-liquid laden air has typically not been considered. Moisture laden air can be pushed out of a pod, when a user exhales through a pod, exerting a pressure in the opposite direction of the intended airflow. The moisture laden air may condense outside the pod, where the device and pod interact, or it may work its way into the device itself.

As previously noted vaping devices with pressure sensors or switches typically include a channel linking the pressure sensor chamber with the pod/device interface. This allows air to be drawn from the pressure sensor chamber when the user draws on the device, thus triggering activation of the device without requiring other user input. Typically, the pressure sensor is mounted to a printed circuit board (PCB) on which other components, including a processor controlling operation of the device, reside.

When e-liquid laden air is pushed into the device, a condensate may form in the various regions into which the air infiltrates. When the condensate forms in areas where there is exposed circuitry, this can create electrical issues. When condensate forms at the interface between the pod and the device, it will appear to the user as a leaking pod, with all the negative effects of an actually leaking pod.

Some prior art attempts at addressing leaking pods have introduced valves into the design of the pod. One problem with such an approach is that pods are typically low cost disposable items where the introduction of elements with moving parts and tight tolerances such as valves, increases the cost of the pod. As such, ball valves and other check valves have typically been restricted in their application to re-usable pods, and are often only introduced to address filling issues so that they are only introduced within the filling system. Furthermore, it should be understood that mechanical valves often have relatively high break pressures, that is they require relatively high pressure to cause the valve to open. If placed within the airflow passage of a pod, it would result in a requirement that the user draw on the device sufficiently hard enough to exceed the breaking pressure of the valve. Vape device design is typically moving in the opposite direction to provide the user with device activation at as low a pressure as can be provided.

In 1920, Nicola Tesla was awarded U.S. Pat. No. 1,329,559 to a “Valvular Conduit” which is conventionally referred to as a “Tesla Valve”. An example of such a valve is illustrated in FIGS. 4A and 4B. A Tesla Valve differs from many existing check valves in that it does not require moving parts for it to prevent passage of a fluid.

A Tesla valve 100 is comprised of a conduit that has a series of loops linked together. In one direction, illustrated in FIG. 4A as going from the top to the bottom, a flow 102 of any fluid can proceed through the valve which provides a gently curving flow path. This is effectively a permanently open connection.

In FIG. 4B, the Tesla valve 100 is subject to a flow in the opposite direction (bottom to top), which corresponds to the closed direction for the path. The overall flow is represented here as a series of subflows, each starting at a junction in the conduit. A flow 104 is introduced into Tesla valve 100, where it flows with a defined pressure until it reaches junction 114 a. A portion of flow 104 will follow the left-side path, while another portion will follow the right side path of the conduit after junction 114 a. These two portions of the flow 104 will be directed at each other, introducing a flow resistance that is proportional to the flow intensity. A part of the overall flow will proceed past this flow resistance, and is designated flow 106. Flow 106 is illustrated with a less thick line than is used for flow 104, representative of the reduced flow pressure in this section of the Tesla valve 100. Flow 106 will split at junction 114 b into components that again will be directed at each other, introducing flow resistance proportional to the intensity of flow 106. The flow that gets past is indicated as flow 108, which encounters junction 114 c where it again splits and is directed back at itself. The same occurs for flow 110 at junction 114 d, and flow 112 at junction 114 e. After each junction, the strength of the flow is diminished, until it is considered to have been stopped.

FIGS. 4A and 4B show how a Tesla Valve 100 makes use of a fluid flow to create a flow resistance that in series with other static structures sufficiently impedes the flow of a fluid to be considered an effective valve. While a Tesla Valve 100 avoids the use of moving elements, it requires a plurality of serially connected structures, each of which increases the length of the structure. Implementation of such a structure, within a pod to prevent egress of moisture laden air still presents a technical problem due to the confined space within a pod.

To overcome these constraints, a novel design of a pod is presented. In this design, the airflow path is designed differently than in much of the prior art to allow for integration of static flow structures that use the pressure of the user exhalation to act as back pressure on the venting of the user's exhalation.

In the following discussion, language such as top and bottom are used when referring to a pod. For clarity, the end that a user engages with will be understood to be the top of a pod, while the end of the pod that is inserted into a vape device will be understood to be the bottom of the pod. Typically, an airflow path through the pod has a principal axis that is aligned to run from the bottom of the pod to the top of the pod. In some pod designs, there are air flow paths that are not completely straight, but when looked at holistically, the principal axis of the airflow path is still vertical (e.g. bottom to top). A forward airflow direction should be understood to refer to the direction of airflow when a user draws on the device, which in the figures above would be illustrated as from the bottom of the pod towards the top. A reverse airflow direction should be understood to refer to the direction of the airflow when a user blows air into the top of the pod, generating a top to bottom airflow direction.

In the example embodiment discussed below, a transition away from a unibody construction end cap is continued. It should be understood that although demonstrated using a multi-part end cap, this is done for ease of implementation and should not be considered to be limiting in scope. Embodiments of the present invention can be implemented in a unibody style end cap without departing from the intended scope of protection, which will be exclusively defined by the claims below.

FIG. 5 illustrates the cross section of an end cap 120 comprised of an end cap base 122 and an end cap top 124. End cap base 122 provides apertures 126 for housing an electrical contact, and defines a pre-wick airflow passage 128 that will be discussed in greater detail in conjunction with other figures below. End cap base 122 is typically formed of a rigid resin or plastic, and may be formed through injection molding or other suitable fabrication technique.

End cap top 124 is designed to engage with end cap base 122, and in the illustrated embodiment, this may be a mating engagement. End cap top 124 may be formed of the same or a different material than the end cap base 122. In some embodiments, end cap top 124 may be formed of a resilient material such as silicone.

End cap top 124 provides an atomization chamber 130 that connects to pre-wick air flow passage 128 through inlets 132. Illustrated within atomization chamber 130 are optional pre-wick airflow features 134, illustrated here as a sawtooth pattern within the wall of atomization chamber 128. Not illustrated in this figure is a wick holder designed to engage with the end cap top 124 to hold in place a wick and heater within the atomization chamber 130.

FIGS. 6A and 6B illustrate a top view of an end cap base 122. This top view will first introduce some of the structure of this end cap base 122, and will then be used to show how it makes use of passive structures to increase the flow resistance to user-induced backpressure (or any backpressure) through the pod. As shown in FIG. 6A, end cap base 122 has structures 126 that allow for electrical contacts to be seated. From the top view, electrical contact structure 126 will appear as a domed cylinder. Pre-wick air flow passage 128 is horizontally aligned in contrast with the prior art illustrated in previous figures. Within end cap base 122, there is a pre-wick air flow passage 128 that takes the form of a plateau around raised features such as airflow guide 138 which includes within its area the electrical contact structure 126, and leads towards vents 136. Airflow guide 138 is a projection that is designed to create airflow paths to enable differential flow resistance based on the direction of the airflow. In some embodiments, airflow guide 138 directs airflow paths starting at end cap inlet 136 to lead them through pre-wick airflow passage 128. In other situations, airflow guide 138 impairs airflows directed out of the pod through end cap inlet 136, as will be explained with reference to FIG. 6B. A fence 140 circumscribes the pre-wick air flow passage 128, and creates a path that allows ingress of air in a preferred direction, and impedes the egress of air in an opposing direction.

FIG. 6B illustrates airflow paths for both attempted egress airflows 142 a and 142 b, and ingress airflow 144. With reference to FIG. 5, it should be understood that the airflow connection between the end cap base 122 and the end cap top 124 is in the center of each. An ingress airflow is typically initiated with a user drawing on the device causing ingress of air through the end cap base 122. The user drawing on the pod-device combination creates a negative pressure starting at the top of the pod that pulls air through the post-wick airflow path, the atomization chamber 130, and eventually the pre-wick airflow passage 128. This effectively pulls air from outside the pod into the pre-wick airflow passage 128 through end cap inlet 136. Airflow path 144 is an example of an ingress airflow path, and a similar second path would be formed from each end cap inlet 136 into pre-wick airflow passage 128. Air drawn in through end cap inlet 136 follows ingress airflow path 144 around airflow guide 138 towards the middle of end cap base 122, where it can exit the pre-wick airflow passage 128 on its way to the atomization chamber.

Airflow path 144 is defined, at least in part, by the location of end cap inlet 136 and the egress to the atomization chamber. This defines the start and finish points for airflow path 144. The route taken through the entirety of pre-wick airflow passage is further defined by the airflow guide 138 and the fence 144.

When a user exhales through the pod, back pressure is created that pushes air through the pod in a direction opposite to the intended direction of airflow. The pressure associated with the exhalation would push air from the end of the post-wick airflow passage towards the wick, through the atomization chamber, and into the pre-wick air flow passage 128. Within the pre-wick airflow passage 128, the pressure pushes air from the center of the end cap base 122 towards the airflow guide 138. Air will follow two paths 142 a and 142 b around the airflow guide 138. The volume of air on each of these paths 142 a and 142 b is a function of the sizing of the path. Placement and orientation of the airflow guide 138 can be used to direct more air into path 142 b by constraining the size of the passage between airflow guide 138 and fence 140. As illustrated in FIG. 6B, air flow paths 142 a and 142 b are directed towards each other so that there is a flow resistance generated by the back pressure itself. Where airflow 142 a would normally proceed towards end cap inlet 136, it not only encounters airflow 142 b, but the path towards end cap inlet 136 is narrowed by the design of fence 140. This acts as a further impediment to the moisture laden airflow being able to vent from the pod.

It should be understood that the passive structures within pre-wick airflow passage 128, including airflow guide 138 and the passages created by the placement of fence 140, increase the flow resistance by creating passages of differing sizes and by directing portions of the airflow against other portions of the airflow. A holistic view of the process undertaken when a user exhales into the pod will reveal that it is not essential for the flow resistance introduced in the pre-wick airflow passage 128 to fully prevent egress of air from the end cap inlet 136. Instead, by increasing the flow resistance, it is possible to change the back-pressure induced airflow at its source, the user. Typically a user exhaling into a pod does not make a seal around the outlet end of a pod as they would while inhaling. Instead of a loose seal, the user's mouth is typically at least partially open. By increasing the flow resistance of a path through the pod, it is possible to encourage more of the exhaust air to exit the user's mouth outside the pod. Thus by increasing the flow resistance to this exhalation driven airflow through the pod by use of the passive structure, the moisture laden air is more likely to escape the user's mouth before entering the pod.

This unidirectional flow restriction is not necessarily a valve. Unlike conventional valves, there are no moving parts. Unlike a Tesla valve, there is no requirement for the structure discussed above to include a series of passive structures aimed at impeding the flow in stages until the flow is effectively eliminated. Instead, much like a diode, flow is restricted in one direction, and is allowed in another direction. The restriction is not necessarily complete, sufficient pressure would allow venting of an airflow through end cap inlet 136, much like a breakdown voltage in a diode. For these reasons, the structure may be described as a fluid diode. It should be noted that creating a series of passive structures (in one or both radial directions) within the end cap can be done without necessarily departing from the scope of the present invention. Depending on the dimensions of the pod in question, it should be understood that adding more passive structures may require making the structures smaller, which may have performance effects, including one or both of increased flow resistance to ingress air flows, and a failure to ensure that the flow resistance is sufficiently high for egress air flows due to the smaller nature of airflow guides etc.

FIG. 7 illustrates a perspective view of the end cap base 122 previously described in FIG. 6A and 6B. The end cap base 122 may be manufactured through an additive manufacturing process, such as 3-D printing, or it may be manufactured using conventional injection molding processes. In one embodiment, the end cap base 122 is made of a plastic resin, and is rigid in structure. Electrical contact structures 126 are formed within the end cap base 122 to allow electrical contacts to be seated within the pod, and to allow for electrical power to be delivered from the device to a heater within the pod. Adjacent electrical contact structures 126 are apertures that allow for leads from the heater to be inserted so that they can make contact with electrical contacts within the electrical contact structure 126. In other embodiments, different mechanisms can be provided for connecting electrical leads to the electrical contacts. In some embodiments, the electrical contact may be provided through contacts on a printed circuit board (PCB), which would eliminate the necessity for a structure such as electrical contact structure 126.

From the perspective used in FIG. 7, the layout of fence 140 becomes clearer. Fence 140 defines both a wall that circumscribes the pre-wick airflow passage 128 and, through arms 140 a and 140 b, which extend inside the circumscribed area, it also defines narrowed pathways leading towards end cap inlet 136. By controlling the placement of the fence 140, a differential flow resistance can be created so that ingress and egress air flow paths can be configured to provide different flow resistances. By combining a narrow airflow path connecting end cap inlet 136 to the remainder of pre-wick airflow passage 128, and by placing airflow guide 138 appropriately, an egress airflow can be restricted so that the flow resistance is sufficiently high to encourage redirection of the exhalation derived airflow.

FIG. 8 is a top plan view of an embodiment of an end cap base 122 with a different topological layout than previously illustrated. End cap base 122 has a fence 140 with arms 140 a and 140 b. These arms 140 a and 140 b prevent direct access from the center of the end cap base 122 to vents 136 which allow ingress of air. The arms 140 a and 140 b, along with the placement and orientation of airflow guide 138 restrict egress airflows from reaching end cap inlet 136. As noted above, these structures do not necessarily completely prevent egress airflows from reaching end cap inlet 136, but instead increase the flow resistance to egress airflows to encourage redirection of the airflows at the source. Airflow guide 138, which is shown as encompassing electrical contact structure 126 is tear-drop shaped, with a pointed end oriented to restrict airflows from directly approaching the end of fence 140 a or 140 b and passing towards end cap inlet 136. The airflow guide 138 encourages an egress airflow to be split into components that are directed towards each other, to increase the flow resistance before the airflow can pass a narrowed section creased by the fence 140 and one of the fence arms 140 a or 140 b. The open area of endcap base 122 circumscribed by fence 140 forms pre-wick airflow passage 128.

Taken in the context of a complete pod, the airflow passage through the pod has a principal axis (typically considered to be a vertical axis) that passes through the atomization chamber and the post-wick airflow passage. In contrast with the illustrated prior art, the pre-wick airflow passage 128 is substantially perpendicular to the principal axis. It should be understood that in various embodiments, the pre-wick airflow passage 128 need not be any of symmetrical, flat or perpendicular to the principal axis, but by making use of the lateral space available in an end cap, the above described embodiments allow for the placement of passive airflow features that allow for a sufficient increase in the flow resistance (for egress airflows in the end cap) that the fluid diode effect can be produced.

FIG. 9 illustrates a perspective view of the end cap base 122 illustrated in FIG. 8. End cap base 122 includes fence 140 which circumscribes pre-wick airflow passage 128, as well as arms 140 a and 140 b, which along with airflow guides 138 define the shape of pre-wick airflow passage 128. This defined shape allows ingress airflow, starting at end cap inlet 136, to proceed with a low flow resistance, but creates a high flow resistance for egress airflows.

Although illustrated in the above figures as forming a flat base to pre-wick airflow passage 128, end cap base 122 may, in some embodiments, have a topology that places different features at different heights. In one example, end cap inlet 136 may be provided in an elevated platform, or it may be surrounded by a wall that does not fully extend to the same height as fence 140. This would allow for collection of e-liquid that has condensed from moisture laden airflow, but would provide an impediment to the egress of this collected e-liquid from vents 136. Where prior art pod designs provide no mechanism to prevent egress of moisture laden airflows, and as such allow for e-liquid condensation to accumulate at the pod device interface, the above described designs can be used to provide sufficient flow resistance to prevent most moisture laden airflows from being pushed through the pod. For any e-liquid condensate that does form, a raised or fenced off end cap inlet 136 will serve to prevent egress of this condensate.

The design of an end cap having passive air flow structures to create a pre-wick airflow passage 128 that imposes flow resistance on egress airflows, while allowing ingress airflows to pass through with relatively low flow resistance, allows for a pod to provide functionality that might only be able to be offered in other embodiments through the use of moving or active components. The high flow resistance experienced by egress airflows makes it difficult to force an exhaled moisture laden airflow through the pod. This encourages a user (consciously or subconsciously) to direct the exhalation out of the pod, avoiding the problems associated with condensation of e-liquid in the interface between the pod and device.

In the above discussion, the end cap base 122 is arranged in a symmetrical fashion. This should be understood as a design choice that is not essential for operation. Other embodiments may avoid a central outlet providing airflow to the wick. Instead, one end cap base inlet and one outlet can be provided at opposing ends of the end cap base 122. This would create a longer airflow path between the inlet and outlet, which would enable the creation of a series of passive structures such as airflow guides 138 to create a longer fluid diode. This fluid diode could in some embodiments resemble a two stage (or longer) Tesla Valve.

In other embodiments, the inlet could be centered within the end cap base, with an outlet at an edge (or two outlets at opposing locations along the circumference of the end cap). This would allow for a central positioning for the end cap inlet, which is similar to many existing pod designs. It should be understood that the placement of the inlet and outlet is only limited by a requirement for sufficient space between them to allow for the passive flow control structures that enable the fluid diode to operate. The offset inlet and outlet in the illustrated figures allows for a compact endcap through the use of a fluid diode that has airflow perpendicular to the primary axis of airflow through the pod. It should be understood that flow guides 138, and the fence 140 (including arms) are both considered to be flow control structures, as would any other structure, such as internal walls, that define a flow path or otherwise direct an airflow.

Those skilled in the art will appreciate that in an alternate embodiment, a pod may be designed to mate with a device, where the features of the above-described end cap base that enable the fluid diode could be provided in the vaping device instead of in the pod. This may allow for the use of different (e.g. more expensive) materials to build the passive airflow features that could allow for a multi-stage passive structure to be provided without as many concerns about the stability, strength and durability of the structures as there would be if implemented in a low cost resin. By placing a fluid diode on the device side of the device-pod interface, existing vaping systems could allow for current pods to be maintained on the market and for these existing pods to be provided some of the benefits of a fluid diode without requiring redesign of the pod. A redesign of the physical structure of the device could effectively provide a retrofit to prior art pods to address issues associated with the backflow of fluids including both e-liquid and e-liquid laden air. When locating components associated with the fluid diode within the device, these components can be placed at the physical interface between the pod and the vaping device. This can allow for an extension of the airflow path within the pod into the flow diode within the device. The flow diode would then provide the differential flow resistance that is discussed above. It should be understood that the device would typically contain a battery connected to electrical leads that allow for power transfer from the battery to the pod. The transfer of the power would be controlled by a processor that can act upon a user input to provide power to the pod when needed, and prevent power transfer at other times. The processor may also control other elements within the device for other purposes (e.g. control of the instantaneous and average power levels being delivered to the pod).

Just as the end cap base could be implemented in one of the pod and the device, it would be possible to implement the fluid diode using structures split between the pod and the device. In one example, the inlets 136 and fence 140 could remain within the end cap base of a pod, while the air flow guides could become features on the device that when mated with an appropriate pod protrude into the end cap to complete the passive airflow structures that enable a fluid diode. In another embodiment, the device side of the device-pod interface could have protrusions that when mated with the pod provide the fence arms 140 a and 140 b (or provide only one of them). This would enable the device to interact with elements within the pod to provide an airflow path that aids in the creation of the fluid diode.

It should be understood that in these alternative embodiments design variations may be employed to change the look and shape of the passive airflow features, but the function of the overall set of features will remain the same.

Although presented below in the context of use in an electronic nicotine delivery system such as an electronic cigarette (e-cig) or a vaporizer (vape) it should be understood that the scope of protection need not be limited to this space, and instead is delimited by the scope of the claims. Embodiments of the present invention are anticipated to be applicable in areas other than ENDS, including (but not limited to) other vaporizing applications.

In the instant description, and in the accompanying figures, reference to dimensions may be made. These dimensions are provided for the enablement of a single embodiment and should not be considered to be limiting or essential. The sizes and dimensions provided in the drawings are provided for exemplary purposes and should not be considered limiting of the scope of the invention, which is defined solely in the claims. 

1. A pod for storing an atomizable liquid, for use in an electronic vaporizer, the pod comprising: a reservoir for storing the atomizable liquid; an atomization chamber, within an airflow path, housing a heater for atomizing the atomizable liquid into an airflow within the airflow path; and a fluid diode within the airflow path for providing a first flow resistance to airflows moving in a forward direction and for providing a second flow resistance, greater than the first flow resistance, to airflows in a reverse direction.
 2. The pod of claim 1 wherein the atomizable liquid is an e-liquid comprising at least one of propylene glycol, vegetable glycerin, nicotine and a flavoring.
 3. The pod of claim 1 further comprising a wick for drawing the atomizable liquid from the reservoir towards the heater within the atomization chamber.
 4. The pod of claim 1 wherein the fluid diode is within a pre-wick airflow passage.
 5. The pod of claim 4 wherein the pre-wick airflow passage is connected to the atomization chamber.
 6. The pod of claim 1 wherein the fluid diode is comprised of a plurality of passive airflow structures.
 7. The pod of claim 6 wherein the plurality of passive airflow structures include at least one of an air flow guide and a fence.
 8. The pod of claim 6 wherein the plurality of passive airflow structures comprises a first airflow guide for splitting airflows moving in a reverse direction into a plurality of airflows, and for directing each of the plurality of airflows towards each other, and a first fence for providing a narrowed airflow passage towards an end cap inlet.
 9. The pod of claim 8 further comprising a second airflow guide and second fence arranged as a reflection of the first airflow guide and first fence.
 10. The pod of claim 8 wherein the first and second fence are a single fence.
 11. The pod of claim 1 wherein the fluid diode connects an end cap inlet to the atomization chamber.
 12. The pod of claim 11 wherein an interface between the fluid diode and the atomization chamber is a set of inlets.
 13. The pod of claim 1 wherein the airflow path is arranged about a principal axis.
 14. The pod of claim 13 wherein the fluid diode is oriented to be substantially perpendicular to the principal axis of the airflow path.
 15. A vaping device for controlling the application of power to a pod containing an atomizable liquid, the device comprising: a battery for storing power; a set of electrical leads for interfacing with the pod to provide power from the battery; a processor for controlling the application of power from the battery to the electrical leads in accordance with a received user input; and a fluid diode at a physical interface between the vaping device and the pod, for mating with the pod to extend an airflow path within the pod into the vaping device, and for providing a first flow resistance to airflows moving through the airflow path in a forward direction and for providing a second flow resistance, greater than the first flow resistance, to airflows moving through the airflow path in a reverse direction.
 16. The vaping device of claim 15 wherein the atomizable liquid is an e-liquid comprising at least one of propylene glycol, vegetable glycerin, nicotine and a flavoring.
 17. The vaping device of claim 15 wherein the fluid diode is comprised of a plurality of passive airflow structures.
 18. The vaping device of claim 17 wherein the plurality of passive airflow structures include at least one of an air flow guide and a fence.
 19. The vaping device of claim 15 wherein the airflow path within the pod is arranged about a principal axis, and an airflow path through the fluid diode is substantially perpendicular to the principal axis. 